The use of halocyanoacetamides in various compositions as antimicrobials is well known for various applications as described in U.S. Pat. No. 2,419,888; U.S. Pat. No. 3,493,658 and Belgian Patent No. 668,336. Certain of the compounds are useful as slimicides in aqueous systems such as paper pulp and others are useful in the finishing of textiles.
In the preparation, storage, shipment and use of antimicrobial agents it is often desirable to employ the agents in the form of liquid concentrate compositions. The properties which are sought for such concentrates include stability over extended periods under a variety of conditions of temperature, humidity, freeze-thaw cycles and the like, compatibility with conventional container materials, and ready diluability in the formulation of treating compositions. A liquid concentrate composition containing a halocyanoacetamide and having the above properties has been long sought.
According to U.K. Pat. No. 1,321,323, there are provided liquid antimicrobial compositions comprising from 1 to 60% halocyanoacetamide in an organic liquid selected from straight chain polyalkylene glycols of the ethylene or trimethylene series and low alkyl ethers thereof, the organic liquid having an average molecular weight of from 135 to 600. This patent discloses that many common organic solvents, such as diethyl ether, ethylene glycol, polypropylene glycol, etc, are unsuitable for use with bromocyanoacetamide, since the concentration of the latter decreases rapidly in relatively short periods of time due to decomposition. Such decomposition is often accompanied by the appearance of colored decomposition products and tarry residues, and the formation of solids. The same patent also discloses that halocyanoacetamide compounds, while active in the presence of water, possess insufficient storage stability in aqueous concentrate solutions to permit convenient storage and shipping of aqueous concentrates. Substantial losses in active ingredient concentration and antimicrobial potency often occur after such storage.
The British patent contains a specific example showing that when bromocyanoacetamide is stored in a concentrated solution in polypropylene glycol 400, a yellow color rapidly develops turning to a brown discoloration with formation of a precipitate after eight days of accelerated aging. Furthermore, more than 80% of the initial bromocyanoacetamide concentrate is lost. Another example specifically shows that using the preferred solvent, polyethylene glycol 200, the addition of up to 16 parts by weight of water does not change the results which are obtained in the absence of water, but more water destroys the effectiveness of the solvent and leads to a loss of bromocyanoacetamide concentration.
In order to reduce the adverse impact of water upon said composition, the prior art describes a series of stabilizers, such as azines, quaternary ammonium or phosphonium compounds, etc. (see for example Israeli patent application No. 55,863 and U.S. Pat. No. 4,163,795).
U.S. Pat. No. 4,022,605 to Konya et al discloses a composition including halocyanoacetamide in a solvent with 0.01-10 weight % of a stabilizer. The solvent may be a polyol, such as polyethylene glycol 200. The stabilizer may be 1,2-propanediol or 1,3-propane-diol. There is no disclosure in Konya of the use of a propane-diol as a solvent or the presence of water for any purpose.